Terms Used

Aw

Type I Allergies

Aw (organic substrate)=ERH/100 (air), where ERH is the equilibrium relative humidity. In other words, aw refers to the available water on a surface, expressed as a percentage. aw numbers quoted refer to a range of minimum water requirements.

Atopic and Anaphylactic Hypersensitivity. This involves localized acute reactions in genetically susceptible individuals to allergens such as pollens, fungi, animal dander, house dust mites, and certain foods. When the allergen contacts the respiratory tree, nasal mucosa and conjunctiva, it may trigger the symptoms of asthma or hay fever. These reactions are mediated by human antibody immunoglobulin E (IgE) which, when fixed to mast cells, react with antigen, triggering release of histamine and activation of slow-reacting substance (SRS-A) and eosinophil chemotactic factor (ECF-A). This mechanism is also responsible for urticaria and angioedema.

Type II Allergies

Type III Allergies

Type IV Allergies

Antibody Dependent Cytotoxic Hypersensitivity. This involves human immunoglobulin antibodies and complement reacting with the antigen on specific target cells that then cause destruction of cells. This occurs in certain types of drug reactions, transfusion reactions, autoimmune hemolytic anemia and Rh blood group incompatibility.

Immune Complex Mediated Hypersensitivity. This involves a reaction between antigen-antibody and complement that form insoluble complexes at fixed sites. The complexes give rise to acute inflammatory reactions, local damage from vascular permeability changes, and from phagocytes that release granules containing proteolytic enzymes. Examples are serum sickness, and hypersensitivity pneumonitis such as farmer’s lung caused by inhalation of dust from moldy hay containing high numbers of thermophilic actinomycetes or other microorganisms.

Category Definitions

Distribution (Outdoors)

Where Found (Outdoors)

Mode Of Dissemination (Outdoors)

This category describes the occurrence of each fungus in nature. Cosmopolitan fungi are found in most parts of the world and under varied ecological conditions. Ubiquitous fungi are encountered frequently and are widespread. For a few fungi, the climatic zones where these fungi are found are also described.

This category describes where the fungus is found in nature, which outdoor habitats it prefers and where it has been reported or isolated. Common habitats are leaves, wood, soil, decaying plant debris, cereal crops and grasses.

This category describes how fungal spores are spread in nature. The most common means of dissemination are wind, rain splash, high humidity, and insects. Insects disseminate spores mechanically when spores adhere to insect body parts, and also by ingesting and depositing spores as fecal pellets.

Allergen (Possible Allergic Effects On Humans)

Potential Opportunist Or Pathogen (Possible Effects On Humans)

Potential Toxin Production

The allergenicity of some of the common fungi have been studied (Alternaria, Cladosporium, Penicillium, Aspergillus, and others) but many of the fungi have not been well studied. The lack of standardized fungal extracts for skin testing and serum antibody testing has made assessment of fungal allergy difficult. Additionally, allergic reactions are complex immune responses to a variety of biological and chemical substances, including fungal antigens. The response varies with individuals, and is dependent upon factors such as familial predisposition, length and dose of exposure(s), prior sensitization, age, and route of exposure. Where allergic reactions have been studied to specific fungal antigens, reactions may vary from immediate (minutes) to delayed (hours to days). Although allergic reactions have been classified traditionally into four types, Type I, II, III and IV, allergic disease may be caused by more than one type. For example, the immune injuries of hypersensitivity pneumonitis are reported to be combined between Type I and III or predominantly Types III and IV.

This category describes some of the toxins produced by particular fungi on natural substrates, on food, or under experimental laboratory conditions. Many of the toxins are secondary metabolites and are not required for survival or growth of the fungus. Reports of toxin production from many studies are not necessarily comparable to metabolic products produced in indoor environments. It should also be kept in mind that toxins may or may not have effects on people or animals (see commentary).

Growth Indoors

Industrial Uses

Other Comments

This category describes some of the common indoor surfaces where fungi are reported to grow and the frequency with which the fungus is reported. Specific conditions of water availability needed for growth on surfaces (aw ­ see definition at the end of this paragraph) are given where it is known. Examples of indoor surfaces that are commonly colonized by fungi under damp or wet conditions are paper products, straw and jute products, cork, wood, leather, books, ceiling tile, gypsum board and associated paper, wood, lumber, textiles, and painted walls.

This category is included to provide a sense of the many positive roles fungi play in everyday life. Historically, fungi have been used to ferment a wide variety of food products and to produce a broad range of chemicals, including therapeutic agents.

This category is included to describe an interesting aspect, a unique feature, or a characteristic of the fungus that may be helpful in understanding its role in the environment.

Characteristics: Growth/Culture

Notes On Spore Trap Recognition (Laboratory Aspects)

Notes On Tape Lift Recognition (Laboratory Aspects)

This category is included for those individuals interested in the appearance of fungal growth on laboratory media and on environmental surfaces. It is not intended to be a complete description of all aspects of growth. Rather, colors and certain colony characteristics that are useful for identifying some fungi are mentioned. Some of these characteristics may have relevance to field investigators.

This category describes certain aspects of spore trap analysis that may assist with correlation and interpretation of other laboratory data (see example below). It is not intended to be a complete microscopic description of each spore type. Spore morphology may be so unique that identification to genus and even species is possible. Other less unique spores may require placement into broader groups of fungi. By providing these comments, it is hoped the reader will gain a better understanding of the advantages and limitations of spore trap analysis.

Example: The field investigator may wonder why the high colony counts of Beauveria seen on Andersen samples are not reflected in the spore trap results. The information in this category explains that Beauveria spores are so small that they may be missed on spore trap samples.

This category describes some of the aspects of tape lift analysis, such as whether the fungus is commonly seen on tape lift samples and, if seen, whether it is readily identifiable. It should be remembered that all comments refer to tape lifts received in our laboratory.

The following are some additional comments on tape lift samples:

When fungal elements are lifted from a surface by sticky tape, all or only part of the fungal structures may be present, allowing either identification to genus (and in some cases species) level or only partial identification to a group level, e.g. Basidiomycetes, Myxomycetes, or Penicillium/Aspergillus.

In some cases, the condition or age of the growth may play a role in recognition. For example, when growth is active or has been undisturbed and all fungal sporulating structures are visible Penicillium and Aspergillus are readily identifiable.

For some fungi, cultivation in the laboratory may be required for further identification. For example, where tape samples reveal only hyphae with no associated spores, cultivation may induce sporulation, making identification possible.

In cases where the recognition of small and delicate sporulating structures are necessary for a more definitive identification, (for example with Beauveria, Engyodontium, Sporothrix, and similar fungi), some tape lift samples may not have enough optical clarity to allow for adequate resolution of such detail.

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and specializes in analyzing samples to identify mold, bacteria (including Legionella,
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